So I need to pull the exepertise of the gearheads in the group-

Sorry its not S2K related- but its on my new project car-

to be competitive I'm gonna need to drop a 5.12 into my FC3S RX7 for SCCA ITS. Just as everyone talks about dropping Junkyard rear ends off of trucks and other cars into S2k's does anybody have any idea how I would figure out what other cars would come stock with an applicable ring and pinion. I'm really trying to get around dropping $1000+ on a rearend as the mazda competition version still needs to be modifyed to fit.

Any input would be appreciated

 

You might try ordering the parts you need from here:

http://www.ring-pinion.com/

 

Great website - thanks!

 

go to a mazda dealer, order a 4.10, 4.44, 4.77 ring and pinion from a 94-97 miata.